Electrical device power management

ABSTRACT

An electrical device includes a memory storing a value indicative the remaining available rated capacity of one or more batteries. The stored value is changed in use to reflect reducing capacity. The initial stored value is chosen so that there is a very high (e.g. &gt;99.9%) confidence that the one or more batteries will provide at least the capacity indicated by the initial stored value. This reduces the chance of failure during emergency procedures. The one or more batteries may be integral to the electrical device. An override facility is provided.

FIELD OF THE INVENTION

The invention relates to electrical devices, including electricalmedical devices, which are powered by batteries and which are operatedin environments where they may come into contact with liquid.

BACKGROUND TO THE INVENTION

Electrical devices, such as electrical medical devices, may incorporatea battery power supply to enable them to be used without the limitationsof a power cable.

A known problem with battery powered electrical devices, includingelectrical medical devices such as laryngoscopes, is that the batteriesmay be depleted and the power supply may fail during use. The batterycompartments of such devices will typically receive any of a wide rangeof batteries having a similar external shape but substantially differentelectrical properties and capacities. Furthermore, it may not beapparent if a battery has been used before. Thus, it may not be possibleto predict exactly when the power supply may fail. Thus, in many knowndevices, there is a substantial risk of a failure in the power supplyduring use. This is of particular concern in relation to electricalmedical devices, such as laryngoscopes, which may be used in emergencyprocedures. This risk of a failure in the power supply can be reduced byusing new batteries for each procedure. However, this is very wasteful.

Accordingly, some aspects of the invention aim to provide improvedmethods of minimising the risk of the battery power supply of anelectrical device failing during a procedure.

Furthermore, many such electrical devices may be used in environmentswhere they may come into contact with liquid. For example, electricalmedical device for in vivo use may be used in environments where theycome into contact with bodily fluids and electrical medical deviceswhich include reusable portions requiring decontamination between usesmay be used in environments where they come into contact with cleaningproducts.

It is often necessary for such electrical devices to be sealed againstpenetration by liquid to prevent damage to the device or loss of batterypower.

A secondary concern is to avoid gaps leading to spaces where microbescan proliferate, and which can be prove difficult to clean.

Thus, the aim of some embodiments of the invention is to provide anelectrical device (for example, an electrical medical device such as alaryngoscope) which is reliably sealed against penetration by liquid.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided anelectrical device comprising an electrical device body, one or morebatteries and a memory storing a value indicative of the remainingavailable rated capacity of the one or more batteries, the electricaldevice comprising a usage recording device operable to determine whenthe electrical device is operated and to update the value stored in thememory responsive to such usage to reflect the consumption of power fromthe one or more batteries resulting from the said operation.

The stored value is therefore the remaining available rated capacityvalue initially stored in the memory, updated by the actions of theusage recording device. After sufficient use the stored value will beindicative that the initial rated capacity of the one or more batterieshas been consumed, for example, the stored value may be progressivelyreduced until it reaches a value, such as zero, indicative that theavailable rated capacity has been consumed.

By the rated capacity we refer to the amount of power which can beobtained from the one or more batteries, while the batteries haveelectrical properties (such as potential difference) sufficient to powernormal operation of the electrical device, according to a predetermined(rated) specification of the amount of power which the one or morebatteries should provide in a very high proportion of cases. Theremaining available rated capacity is the amount of that rated capacitywhich has not yet been consumed as updated by the usage recording deviceduring use.

The value of remaining available rated capacity initially stored in thememory is selected so that, in a very high proportion of cases,typically at least 99% and preferably at least 99.9% or at least 99.99%of cases, the one or more batteries will have remaining stored powerwhich could be used to power normal operation of the electrical devicewhen the stored value reaches a value indicative that the rated capacityhas been exhausted. Thus, if the one or more batteries in aggregate arefound to deliver 105.0 to 175.0 mAh in 99.9% of cases, taking intoaccount the range of uses to which the electrical devices are put, thevalue initially stored in the memory well be set so that it is updatedto a value indicative that the initial capacity has been consumed whenat most 105.0 mAh have been used.

As a result of this margin for error, if the stored value is indicativethat an amount of capacity exceeding that required for a procedureremains stored in the one or more batteries, the user can have a veryhigh confidence that the electrical device will continue to operatethroughout the procedure, reducing the risk of failure which couldotherwise occur in devices which enable a user to use any battery of aspecific class which encompasses batteries having very differentcapacities (e.g. AA or AAA batteries, which have compositions andcapacities which vary widely between brands and types, for exampleAlkaline, NiMH or Lithium).

The use of stored values which are updated when use occurs can provide amore accurate estimate of guaranteed remaining capacity than the use ofmeasurements of remaining battery capacity, which can be unreliable,especially when the battery capacity is close to exhausted.

The one or more batteries may be provided in a battery pack comprisingthe one or more batteries. The battery pack may comprise the memory.

The usage recording device typically determines when use is occurringand transmits signals to the battery pack indicative that the valuestored in the memory should be updated. The signals may represent anupdated value to be written to the memory, or that the stored valueshould be changed by a certain amount, for example, incremented ordecremented. The usage determining module may communicate wirelesslywith the battery pack. For example, the memory may be part of an RFIDtag located in the battery pack, read from and written to by a solenoidaerial in the body of the electrical device.

In some embodiments the electrical device comprises a removable batterypack comprising the one or more batteries and the memory. Thus, theremovable battery pack includes a memory storing a value indicative ofthe remaining available capacity of the one or more batteries in theremovable battery pack. The battery pack may lack a recharge interface.For example, the battery pack may lack an external power input.

However, in some embodiments, the one or more batteries (e.g. batterypack) is integral to the electrical device body such that the user maynot remove the battery pack from the electrical device body. The one ormore batteries (e.g. battery pack) may be mounted to (for examplewithin) the electrical device body. The electrical device body (and thebattery pack in embodiments where the battery pack defines at least partof the outer surface of the electrical device) may be covered with asealing layer, for example of a fluid resistant material, such assilicon, to form a continuous surface around the electrical device, forexample, around a handle of the electrical device. Therefore, the one ormore batteries (e.g. battery pack) may be sealed from any potentiallyhazardous solvent, such as water or a non-aqueous solvent used forcleaning the electrical device, for example.

The sealing layer may allow the electrical device to be fullysubmersible, that is, electrical device may be fully submerged in water,for example, without suffering damage.

Preferably, the one or more batteries are disposable batteries. That is,the one or more batteries may not be recharged after the available ratedcapacity of the one or more batteries has been consumed. In someembodiments, the one or more batteries may be rechargeable batteriesintegral to the electrical device and the electrical device may lack aninterface for recharging the batteries. Thus, the user cannot rechargethe batteries, although a manufacturer or their agent might do so, afterdismantling the electrical device. Alternatively, the manufacturer ortheir agent may recharge the one or more batteries wirelessly (forexample, using a capacitive charger). Typically, the one or morebatteries cannot be removed without breaking a part (e.g. a sealinglayer). This avoids the risk of a user changing one or more batteries,or recharging them, leading to a situation where the amount of remainingpower cannot be guaranteed and there is a risk of the electrical devicefailing during a procedure (e.g. failing during intubation in the caseof a video laryngoscope).

Therefore, the electrical device must be replaced when the availablerated capacity of the one or more batteries has been consumed.

Where the electrical device is only intended for infrequent use (forexample, less than 20 applications a year) one or more integralbatteries that may not be replaced or recharged in situ allows theelectrical device to be thoroughly sealed with a continuous layer ofmaterial, providing a minimum number of features such as creases, withinwhich contaminants such as bacteria, for example, may grow. In addition,the electrical device with one or more integral batteries allows forsimplicity of construction, a lower cost of parts (as there may be fewerparts) and a higher reliability (as there may be fewer moving parts)than a similar electrical device with at least one removable battery,for example.

Alternatively, the electrical device may be intended for frequent use(for example, the one or more batteries may hold enough charge for 400minutes of use, 800 minutes of use or more than 1000 minutes of use.

During the lifetime of rechargeable batteries, the maximum availablerated capacity degrades as the battery is repeatably recharged. Inaddition, the characteristics of the rate of change of the availablerated capacity as the battery is used may be changed or degraded,resulting in inaccurate values of available rated capacity. Suchinaccuracies could lead to failure of the device during use.

Accordingly, the use of disposable batteries ensures that the storedvalue of available rated capacity is accurate and dependable such thatdevice failures during use, due to the batteries become depleted, areeffectively eradicated.

It may be that the memory is a passive device such that power is onlyconsumed by the memory when data is read from or written to the memory.Thus, where the memory is part of an RFID tag, the RFID tag ispreferably a passive RFID tag.

The stored value may be numerical value representing remaining availablerated capacity. The stored value for a new fully charged battery packmay have a predetermined integer value, such as 100, 256, 500 etc. whichis progressively decremented by the memory updating module in use, and abattery which has output its rated amount of power would have a storedvalue of zero. The stored value may count up. The value may be stored inany form, for example, the memory may comprise a plurality of fuses orantifuses which are triggered in turn with the number of fuses orantifuses which have been triggered or which remain untriggeredindicating the stored value.

The stored value may be indicative of a number of units of time, such ashours or minutes, of operating of the electrical device (optionally, inone or more modes) for which the battery pack has remaining availablerated capacity for a given power consumption. This is especially helpfulwhere the power consumption of the medical device is substantiallyconstant in use. The stored value may be indicative of a number ofprocedures which the electrical device can carry out using the remainingavailable capacity (for example, intubation procedures where theelectrical device is a video laryngoscope).

The electrical device may display an indicator of the amount of capacityremaining in the battery pack based on the stored value. The indicatormay comprise a light source or a plurality of light sources. Theplurality of light sources may comprise light sources which emit lightof a different colour to each other. The electrical device may comprisea screen and the screen may display the indicator. For example, wherethe electrical device is a video laryngoscope having a screen, thescreen may display the indicator. The indicator may be a number. Theindicator may be a number representative of an amount of time, or anumber of procedures which the electrical device can carry out using theremaining available capacity (for example, intubation procedures wherethe electrical device is a video laryngoscope).

The electrical device may comprise a loudspeaker and generate a soundindicative that the remaining capacity determined from the stored valueis approaching zero.

The electrical device may stop, or not start, carrying out one or moreoperating functions once the remaining available rated capacityindicated by the stored value is below a threshold (for example, a fewpercent of maximum capacity, or zero, or a predetermined negativevalue). The electrical device may indicate one or more warning to a userbefore this occurs.

The electrical device may comprise an override to enable a user tocontinue to carry out, or to start, some or all of the operatingfunctions even though this has occurred. The override may comprise aswitch. The override may comprise a microphone and allow a user tocontinue to carry out, or to start, some or all of the operatingfunctions responsive to a sufficiently loud sound detected by themicrophone (e.g. the user shouting at the device from close range). Thisis advantageous as it allows a user to obtain additional function whererequired, but it dissuades a user (who would typically not wish to shoutin certain environments) from using an override activated by asufficiently loud sound. The override mechanism may comprise a switch,or another form of user input such as pressure sensors or sound sensors,for example.

Typically, an electrical device is an electrical medical device. Themedical device may be a handheld medical device, such as an ultrasoundscanner, infusion pump controller and infusion pump, diagnostic device,blood monitor, e.g. blood glucose monitor, endoscopes or other devicesfor probing within the human body.

The electrical device may be an intubation instrument such as alaryngoscope, preferably a video laryngoscope.

In embodiments where the electrical device is a laryngoscope, thelaryngoscope may comprise a handle and an arm. The handle may comprise afirst end adjacent to the arm, and an opposed second end. The one ormore integral batteries may be located within the handle of thelaryngoscope adjacent to the first end.

Preferably, the one or more batteries are located closer to the firstend than the second end. Preferably, the centre of mass of the one ormore batteries is located at least two-thirds, preferablythree-quarters, of the way from the second end to the first end.

The majority of the electronics within the handle of the laryngoscopemay be located closer to the first end than the second end, for example,at least two-thirds (or preferably three-quarters) of the way from thesecond end to the first end. They may be adjacent to the first end ofthe handle.

In embodiments where the electrical device is a laryngoscope and thelaryngoscope body comprises a handle, the provision of the one or morebatteries and/or the majority of the electronics located closer to thefirst end of the handle ensures that the centre of gravity of the handleis closer to the first end of the handle than the second end, andensures that the laryngoscope handle is stabilised within the hand of auser. In addition, the provision of the one or more batteries and/or themajority of the electronics being located adjacent to the first end ofthe electrical device body ensures that the electronics are compact.

The electronics may be mounted onto a printed circuit board (PCB). Theone or more batteries may be mounted onto a PCB. Both the electronicsand the one or more batteries may be mounted onto the PCB. The PCB maybe located in the body. The PCB may be located in the arm. The PCB mayextend from the body into the arm. The PCB may also function as astrengthening element to strengthen the arm.

The second end of the electrical device body may comprise a low densityportion. The low density portion may comprise an air pocket. The lowdensity portion may comprise a low density foam.

Alternatively, the low density portion may comprise a recess in thesurface of the electrical device body. The recess may allow the user togrip the electrical device more securely.

Where the electrical device is a video laryngoscope, the laryngoscopemay comprise a screen connected to the battery and electronics of thelaryngoscope by a connector. The connector may be a physical wire. Theconnector may be an optical connection such as an optical fibre. Theconnector may be a wireless connector or transmitter.

According to a second aspect of the invention there is provided alaryngoscope comprising a handle comprising one or more integralbatteries and a laryngoscope arm extending from the handle, the handlehaving a first end adjacent to the arm and an opposed second end;wherein the one or more batteries are closer to the first end than thesecond end.

DESCRIPTION OF THE DRAWINGS

An example embodiment of the present invention will now be illustratedwith reference to the following Figures in which:

FIG. 1 is a series of side-on plan views of embodiments of videolaryngoscopes;

FIG. 2 is two side-on plan views of demountable sheaths that may bemounted onto a video laryngoscope;

FIG. 3 is an exploded isometric view of a video laryngoscope with thebattery pack removed;

FIG. 4 is an exploded view of the video laryngoscope of FIG. 3 from analternative angle;

FIG. 5 is an exploded view from the front of the video laryngoscope ofFIG. 3; and

FIGS. 6A through 6D are sectional views through the electrical devicebefore the battery pack is mounted (FIG. 6A), after the battery pack ismounted (FIG. 6B), with the battery pack and electrical devicesuperimposed (FIG. 6C) and in expanded view (FIG. 6D).

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS First Embodiment

With reference to FIG. 1 a video laryngoscope 1 (being an example of anelectrical device) comprises a body 2, and an arm 4 extending from thebody. When prepared for use, a disposable rigid plastic sheath 58 or 60is demountably retained on the arm, functioning as a laryngoscope blade.

The body of the video laryngoscope includes a processor unit 44 whichcomprises a memory unit and controls the functions of the videolaryngoscope, including a light 46, a video camera 48, a video display50 for displaying images from the video camera via a wired connection(acting as a connector) 52 and a battery 54 to provide power for thevideo laryngoscope. The surface of the body comprises an activationswitch 22 and a light emitting diode 24 which functions as a displayinforming the user whether the video laryngoscope is activated.

The video laryngoscope further comprises an air gap 56 (acting as a lowdensity portion) at the end of the body opposed to the arm.

In alternative embodiments the air gap may be replaced by low densityfoam or a recess in the surface of the body. Further alternatives maycomprise more than one air gap.

A user begins operation of the device by pressing the activation switch.The device powers up, switching on the video camera, video screen andlight. The processor reads the value stored in the memory unit. When thebattery is new and unused, the value is a predetermined integer, such as500. This value, or a number derived from it, is displayed on the screenas a numeral, or in another graphic format, such as a bar chart, piechart, or any other graphical representation of available capacity.

As the device is used, the processor calculates the amount of usage. Insome embodiments the processor simply determines the period of time forwhich the device is used. As the capacity of the battery is consumed,the value displayed on the screen is changed to reflect the reducedcapacity, for example, the number 500 counts down. Periodically, theprocessor writes a new value to the memory unit, reflecting the reducedavailable rated capacity of the battery. This may be carried out eachtime the stored value should change, or may be carried out once when thedevice is powered down. The value stored in the memory unit can beupdated quickly. As the activation switch is integral to the body of thevideo laryngoscope, a user cannot subvert the usage recording system byremoving the memory unit to prevent the value stored on the memory unitfrom being updated.

The processor may change the stored value depending solely on the amountof time for which the electrical device has been used, or used in one ormore operating modes (e.g. modes in which the video screen is switchedon in the case of a video laryngoscope). The processor may however takeinto account variations in power consumption by the device. More powerwill be consumed when a screen is on, for example, than when it is not.Thus, the processor may decrement the stored value more frequently inoperating modes in which more power is consumed. The electrical devicecould include an ammeter but it is preferred to simply base changes tothe value on measurements of the amount of time for which the device hasbeen used, or used in specific operating modes, for simplicity. Theprocessor may take into account environmental factors, such astemperature, measured by one or more sensors, such as a temperaturesensor (e.g. a thermocouple), as such factors may affect battery lifeand/or power consumption.

Once the remaining available rated capacity of the battery reaches zero,or another threshold value as appropriate, the processor may cause theelectronic device (or at least one function of the electronic device) tostop operating or to no longer start operating. The latter option may bepreferable for a video laryngoscope used in an emergency environments asit could be dangerous for the device to stop functioning during anemergency procedure. It would be safer for it simply to not startfunctioning unless there was sufficient remaining available ratedcapacity to complete a procedure based on the known typical powerconsumption during that procedure. Before the device stops operating, orno longer starts operating, the device will typically output one or moreaudible or visual warnings.

As the stored value was initially chosen so that there was a high levelof confidence that the capacity of the battery would not be exhaustedbefore the remaining available rated capacity reached zero there willvirtually always be some additional battery capacity available, althoughusers should be discouraged from relying on or using this.

The device of the example embodiment also includes an override featureto enable a user to cause it to continue carrying out one or morefunctions, or to start carrying out one or more functions, even thoughthe available rated capacity has dropped below the threshold. This mayinvolve the user pressing a button but could involve another type ofuser interface. For example, the user may have to speak their name(which speech could be recorded), or to emit a loud noise at aloudspeaker of the device by shouting. Thus, an emergency override maybe present but one which a user would not wish to use except in agenuine emergency.

The batteries cannot be accessed by a user and there is no recharginginterface. Thus, there is a high level of confidence in the displayedavailable capacity.

Although the invention has been illustrated with the example embodimentof a video laryngoscope, the invention may also be employed with othertypes of electrical devices.

Second Embodiment

With reference to FIGS. 2 to 5 a video laryngoscope 1 (being an exampleof an electrical device) comprises a body 2, and an arm 4 extending fromthe body. When prepared for use, a disposable rigid plastic sheath (notshown) is demountably retained on the arm, functioning as a laryngoscopeblade. The body portion comprises a first surface region 6, and a recess8 for receiving a battery pack 10.

The body comprises electrical contacts 12 (functioning as an inputinterface) for receiving electrical power from the battery pack, locatedwithin the recess. The battery pack comprises a first major surface 14and a second, opposed major surface 16. The first major surfacecomprises battery retaining formations 18 which retain a battery 20 and,when the battery pack is installed on the body the first major surfacefaces the body. The second major surface comprises an activation switch22 and a light emitting diode 24 which functions as a display informingthe user whether the video laryngoscope is activated. When the batterypack is installed on the body, the second major surface becomes a partof the outer surface of the laryngoscope, forming a grip for a user,along with the first surface region 6. The battery pack compriseselectrical contacts 26 (functioning as an output interface) throughwhich power can be transmitted to the electrical contacts on the body ofthe electrical device when the battery pack is fitted and the device isswitched on.

The battery pack comprises a first seal 28 on a coupling surface 30extending around the perimeter of the battery pack and a second seal 32also located on the coupling surface. The seals are each formed asflexible polymeric ridges. Upon installation of the battery pack ontothe body, the seals are compressed between the coupling surface and acooperating surface 34 of the electrical device forming a waterproofseal around the perimeter of the battery pack.

The battery pack includes an RFID tag 38 including memory 40, and thebody includes a solenoid coil 42 operable to inductively power the RFIDtag (when the battery pack is fitted to the device), to read data fromthe RFID tag memory and to write data to the memory.

The body of the laryngoscope includes a processor 44 which controls thefunctions of the laryngoscope, including a light 46, a video camera 48,a video display 50 for displaying images from the video camera, and thesolenoid coil.

When a battery pack is attached to the body (and so the device is in itsassembled state) the body of the device is coated in a film of material,such as a plastic material to provide a smooth, water proof outersurface of the device. The device is now watertight and the battery packmay not be removed.

A user begins operation of the device by pressing the activation switch.The device powers up, switching on the video camera, video screen andlight. The solenoid coil activates the RFID tag, reading the valuestored in the memory. When the battery pack is new and unused, the valueis a predetermined integer, such as 500. This value, or a number derivedfrom it, is displayed on the screen as a numeral, or in another graphicformat, such as a bar chart, pie chart, or any other graphicalrepresentation of available capacity.

As the device is used, the processor calculates the amount of usage. Insome embodiments processor simply determines the period of time forwhich the device is used. As the capacity of the battery pack isconsumed, the value displayed on the screen is changed to reflect thereduced capacity, for example, the number 500 counts down. Periodically,the processor causes the solenoid coil to power up the RFID tag andwrite a new value to the memory of the RFID tag, reflecting the reducedavailable rated capacity of the battery pack. This may be carried outeach time the stored value should change, or may be carried out oncewhen the device is powered down. The value stored on the RFID tag can beupdated quickly. As the activation switch is integral to the batterypack, a user cannot subvert the usage recording system by removing thebattery pack to prevent the value stored on the RFID tag from beingupdated.

The processor may change the stored value depending solely on the amountof time for which the electrical device has been used, or used in one ormore operating modes (e.g. modes in which the video screen is switchedon in the case of a video laryngoscope). The processor may however takeinto account variations in power consumption by the device. More powerwill be consumed when a screen is on, for example, than when it is not.Thus, the processor may decrement the stored value more frequently inoperating modes in which more power is consumed. The electrical devicecould include an ammeter but it is preferred to simply base changes tothe value on measurements of the amount of time for which the device hasbeen used, or used in specific operating modes, for simplicity. Theprocessor may take into account environmental factors, such astemperature, measured by one or more sensors, such as a temperaturesensor (e.g. a thermocouple), as such factors may affect battery lifeand/or power consumption.

Once the remaining available rated capacity of the battery pack reacheszero, or another threshold value as appropriate, the processor may causethe electronic device (or at least one function of the electronicdevice) to stop operating or to no longer start operating. The latteroption may be preferable for a video laryngoscope used in an emergencyenvironments as it could be dangerous for the device to stop functioningduring an emergency procedure. It would be safer for it simply to notstart functioning unless there was sufficient remaining available ratedcapacity to complete a procedure based on the known typical powerconsumption during that procedure. Before the device stops operating, orno longer starts operating, the device will typically output one or moreaudible or visual warnings.

As the stored value was initially chosen so that there was a high levelof confidence that the capacity of the battery pack would not beexhausted before the remaining available rated capacity reached zerothere will virtually always be some additional battery capacityavailable, although users should be discouraged from relying on or usingthis.

The device of the example embodiment also includes an override featureto enable a user to cause it to continue carrying out one or morefunctions, or to start carrying out one or more functions, even thoughthe available rated capacity has dropped below the threshold. This mayinvolve the user pressing a button but could involve another type ofuser interface. For example, the user may have to speak their name(which speech could be recorded), or to emit a loud noise at aloudspeaker of the device by shouting. Thus, an emergency override maybe present but one which a user would not wish to use except in agenuine emergency.

Once the battery pack has been exhausted the consumed battery packcannot be replaced or recharged by the user. However, the electricaldevice may be returned to the manufacturer who may remove the film andremove the battery pack for recycling, recharging or reconditioning.

The memory of the RFID tag may store additional data, such as anidentifier of the battery pack, or of an electrical device to which itis or has been fitted. Some or all of the data stored on the RFID tag,such as the stored value described above, may be encoded to preventtampering.

Although the invention has been illustrated with the example embodimentof a video laryngoscope, the invention may also be employed with othertypes of electrical devices.

Further variation and modifications may be considered by one skilled inthe art, within the scope of the invention herein disclosed.

1. An electrical device comprising an electrical device body and abattery pack comprising one or more batteries and a memory storing avalue indicative of the remaining available rated capacity of the one ormore batteries, the electrical device comprising a usage recordingdevice operable to determine when the electrical device is operated andto update the value stored in the memory responsive to such usage toreflect the consumption of power from the one or more batteriesresulting from the said operation.
 2. An electrical device according toclaim 1, wherein the value of remaining available rated capacityinitially stored in the memory is selected so that in at least 99% ofcases the battery pack will have remaining stored power which could beused to power normal operating of the electrical device when the storedvalue reaches a value indicative that the rated capacity has beenexhausted.
 3. An electrical device according to claim 1, wherein theusage recording device determines when use is occurring and transmitssignals to the battery pack indicative that the value stored in thememory should be updated.
 4. An electrical device according to claim 1,wherein the battery pack comprises an RFID tag, including the memory,and the body of the electrical device includes as solenoid aerial in thebody of the electrical device to read from and write to the RFID tagmemory.
 5. An electrical device according to claim 1, wherein thebattery pack is integral to the body.
 6. An electrical device accordingto claim 5, wherein the integral battery pack cannot be removed from theelectrical device.
 7. An electrical device according to claim 5, whereinthe integral battery pack cannot be recharged.
 8. An electrical deviceaccording to claim 1, wherein the one or more batteries of the batterypack are disposable batteries.
 9. An electrical device according toclaim 1, wherein the stored value may be numerical value representativeof remaining available rated capacity.
 10. An electrical deviceaccording to claim 9, wherein the stored value is indicative of a numberof units of time of operating of the electrical device, or operating ofthe electrical device in one or more modes, for which the battery packhas remaining available rated capacity for a given power consumption.11. An electrical device according to claim 1, wherein the electricaldevice will stop, or not start, carrying out one or more operatingfunctions once the remaining available rated capacity indicated by thestored value is below a threshold.
 12. An electrical device according toclaim 1, wherein the electrical device comprises an override to enable auser to continue to carry out, or to start, some or all of the operatingfunctions even though this has occurred.
 13. An electrical deviceaccording to claim 12, wherein the override comprises a microphone andthe device allows a user to continue to carry out, or to start, some orall of the operating functions responsive to a sufficiently loud sounddetected by the microphone.
 14. An electrical device according to claim1, which is an electrical medical device.
 15. An electrical medicaldevice according to claim 14 which is a video laryngoscope.
 16. A videolaryngoscope according to claim 15, wherein the video laryngoscopecomprises an arm, a body and a printed circuit board; where the printedcircuit board functions as a strengthening element to strengthen thearm.
 17. A laryngoscope comprising a handle comprising one or moreintegral batteries and a laryngoscope arm extending from the handle, thehandle having a first end adjacent to the arm and an opposed second end;wherein the one or more batteries are closer to the first end than thesecond end.